Yes, it is a major problem but some people tend to overlook it. Smoking can cause problems either now or in the future, but some kids might not care if this a real problem. It can cause a number of problem and severity of respiratory illnesses, decreased physical fitness and some effects on lung function. Smoking is not a way to cope with problems and should never be.
C is the choice I would make because I believe the writer is planning to answer this question: "and how come we think dogs are so smart". The writer never tells us what dogs can't do (a) or mention others being dumb (b) and doesn't make fun of humans (d)
The participle in the sentence (the participle is stacked because it is a verb being used to modify a noun) modifies the word NEWSPAPERS
